Pyridyl-triazine inhibitors of hedgehog signaling

Title: Pyridyl-triazine inhibitors of hedgehog signaling.Abstract: The invention provides pyridyl-triazine derivatives to inhibit the hedgehog signaling pathway and the use of such compounds in the treatment of hyperproliferative diseases and angiogenisis mediated diseases. ...

FIELD OF THE INVENTION

The present invention relates generally to the use of pyridyl-triazine derivatives to treat a variety of disorders, diseases and pathologic conditions and more specifically to the use of triazine compounds to inhibit the hedgehog signaling pathway and to the use of compounds to the treatment of hyperproliferative diseases and angiogenesis mediated diseases.

Two of the functions of Hh in vertebrate embryonic development are both crucial and relatively well understood: neural tube differentiation and anteroposterior limb patterning. The predominant mechanism of Hh signaling in these functions is paracrine signaling, in which the Hh molecules act in a gradient fashion. For example, in vertebrate limb buds, exposure to different concentrations of Shh modulates patterning of the interdigital mesenchyme, which influences the proper growth of digits in a specific pattern (Tabin, C. J.; McMahon, A. P. Science 2008, 321, 350-352). In neural tube development, Shh produced by the floor plate causes dorsoventral patterning, the specification of ventral cell populations, and general cellular proliferation in the brain.40 Holoprosencephaly, a disorder involving the development of forebrain and midface in which ventral cell types are lost, is caused in humans by mutations that lead to loss of Shh activity (Belloni, E.; Muenke, M.; et al., Nat. Genet. 1996, 14, 353-356).

Another important feature of Shh signaling is that the Gli subtypes have both unique and overlapping functions. While ectopic expression of Gli1 in the midbrain and hindbrain of transgenic mice results in expression of some ventral cell types, mice homozygous for a mutation in the region encoding the zinc finger domain of Gli1 develop normally (Hynes, M.; Stone, D. M.; et al., Neuron, 1997, 19, 15-26; Park, H. L.; Bai, C.; et al., DeVelopment 2000, 127, 1593-1605). However, Gli1/Gli2 double mutant mice have phenotypes with severe multiple defects, including variable loss of the ventral spinal cord, and smaller lungs; therefore, Gli2 plays a more important role in spinal cord and lung development than does Gli1. In contrast, Gli1/Gli3 double mutant mice did not have these phenotypes (Park, H. L.; Bai, C.; et al., DeVelopment 2000, 127, 1593-1605). Gli2 and Gli3 have both been implicated in skeletal development, with each subtype serving specific functional roles. Gli2 mutant mice exhibit severe skeletal abnormalities including cleft palate, tooth defects, absence of vertebral body and intervertebral discs, and shortened limb and sternum (Mo, R.; Freer, A. M.; et al., DeVelopment 1997, 124, 113-123). Gli3 appears to be the major mediator of Shh effect in the limbs, as Gli1/Gli2 double mutant mice had a normal digit number and pattern while Gli3 mutant mice showed polydactyly (Hui, C. C.; Joyner, A. L. Nat. Genet. 1993, 3, 241-246).

Genetic analyses of Gli mutants revealed that the requirement for Gli subtypes development is quite divergent even among vertebrates. In zebrafish, both detour (dtr) mutations (encoding loss-of-function alleles of Gli1) and you-too (yot) mutations (encoding C-terminally truncated Gli2) have defects in body axis formation and expression of Hh-target genes in the brain (Karlstrom, R. O.; Tyurina, O. V.; et al., DeVelopment 2003, 130, 1549-1564), suggesting divergent requirements for Gli1 and Gli2 in mouse and zebrafish.

In adults, the Hh pathway is essential for restraining growth in the nervous system and other tissues and in maintenance of stem cells. Zhang and Kalderon have shown that Hh acts specifically on stem cells in Drosophila ovaries and that these cells cannot proliferate in the absence of Hh (Zhang, Y.; Kalderon, D. Nature 2001, 410, 599-604). Other studies showed that Hh signaling in the postnatal telencephalon both promotes proliferation and maintains populations of neural progenitors, suggesting that Shh signaling in the mammalian telencephalon may participate in the maintenance of a neural stem cell niche. The role of Hh in proliferation of adult neural progenitor cells was confirmed by a study in which Shh was overexpressed and proliferation was inhibited by using a Smo antagonist (Lai, K.; Kaspar, B. K.; et al., Nat. Neurosci. 2003, 6, 21-27).

Hh genes have the ability to induce tissue proliferation. This function is important in embryogenesis and tissue maintenance, but inappropriate activation of the pathway can result in tumorigenesis (Hunter, T. Cell 1997, 88, 333-346). Tumors in about 25% of all cancer deaths are estimated to involve aberrant Hh pathway activation. Tumorigenesis or tumor growth can result from abnormal up-regulation of Hh ligand or from deregulation of the expression or function of downstream components by, for example, loss of Ptch, activating mutations of Smo (Xie, J.; Murone, M.; et al., Nature 1998, 391, 90-92), loss of SuFu, amplification or chromosomal translocation of Gli1 or Gli2 gene amplification or stabilization of Gli2 protein (Bhatia, N.; Thiyagarajan, S.; J. Biol. Chem. 2006, 281, 19320-19326).

The first Hh pathway gene found to be amplified in cancers was Gli1, which was expressed at high levels in human glioblastoma and derived cell lines. Subsequently, Gli1 was found to be consistently expressed in a variety of glial tumors, and Gli1 overexpression was shown to induce central-nerves system hyperproliferation (Dahmane, N.; Sanchez, P.; et al., DeVelopment 2001, 128, 5201-5212). Gli1 overexpression has also been observed in a panel of brain tumors ranging from low-grade to high-grade in a study that identified Gli1 expression as the only reliable marker of Hh pathway activity (Clement, V.; Sanchez, P.; Curr. Biol. 2007, 17, 165-172). Further, cell proliferation in primary cultures of many of these tumors was inhibited by Gli1 small-interfering RNA. Gli1 expression was correlated with tumor grade in PDGF-induced liomagenesis in mice. Hh signaling components other than Gli1 also contribute to tumorigenesis in specific subsets of glioblastomas. In PDGFinduced tumors, expression level of Shh was correlated with the tumor grade. However, other studies found only a subset of gliomas to contain high levels of Shh.

Another cancer with defects in Hh pathway regulation is basal cell carcinoma (BCC). Human Ptch was first identified by virtue of its mutation in patients with Gorlin syndrome (GS), a genetic disease that gives rise to sporadic BCC (Johnson, R. L.; Rothman, A. L.; et al., Science 1996, 272, 1668-1671). The mutations of Ptch identified in BCC include deletions producing truncated proteins and insertion or nonsense mutations accompanied by loss of heterozygosity (LOH) or mutations in the other allele. These mutations inhibit the ability of Ptch to suppress Smo, resulting in constitutive Hh signaling. While Ptch1 abnormalities are detected in the majority of BCC patients, it is now clear that a subset of BCC is also driven by a mutation in Smo that decreases its sensitivity to inhibition by Ptch. In addition, overexpression of Gli1 protein causes BCC-like tumors in mice, establishing the importance of Gli1 transcription in BCC tumorigenesis (Nilsson, M.; Unden, A. B.; et al., Proc. Natl. Acad. Sci. U.S.A. 2000, 97, 3438-3443). The level of Gli1 transcript can be used to discriminate BCC from certain other skin tumors (Hatta, N.; Hirano, T.; et al., J. Cutaneous Pathol. 2005, 32, 131-136). However, blocking of Glibased transcription has not yet been shown to arrest BCC growth.

Medulloblastoma, the most common malignant pediatric brain tumor, is linked with mutations in Ptch and Smo and mutations in other Hh pathway genes such as SuFu and Gli (Pomeroy, S. L.; Tamayo, P.; et al., Nature 2002, 415, 436-442). Inactivation of the Ptch locus by deletion and mutation has been found in about 10% of sporadic medulloblastomas. Shh pathway involvement in these tumors was further confirmed by studies in which treatment of murine medulloblastomas with Smo inhibitors inhibited cell proliferation and reduced tumor growth in mice (Berman, D. M.; Karhadkar, S. S.; et al., Science 2002, 297, 1559-1561; Sanchez, P.; Ruiz i Altaba, Mech. DeV. 2005, 122, 223-230; Romer, J. T.; Kimura, H. et al., Cancer Cell 2004, 6, 229-240). Taylor et al. identified SuFu as a tumorsuppressor gene whose mutation predisposes individuals to medulloblastoma. They found that a subset of children with medulloblastoma carry germline and somatic mutations in SuFu, accompanied by loss of heterozygosity of the wild-type allele. Several of these mutations encoded truncated SuFu proteins that are unable to export Gli protein from the nuclei. In addition, the tumor-suppressor REN has also been linked with medulloblastoma in which the allelic deletion and reduced expression of REN are frequently observed. It is suggested that it inhibits medulloblastoma growth by negatively regulating the Hh pathway (C.; Zazzeroni, F.; Gallo, R.; et al., Proc. Natl. Acad. Sci. U.S.A. 2004, 101, 10833-10838; Argenti, B.; Gallo, R.; et al., J. Neurosci. 2005, 25, 8338-8346).

The aberrant activation of Hh-Gli signaling in several cancers has made it an attractive target for anticancer drug discovery. Various inhibitors of hedgehog signaling have been investigated such as Cyclopamine, a natural alkaloid that had been showed to arrest cell cycle at arrest cell cycle at G0-G1 and to induce apoptosis in SCLC. Cyclopamine is believed to inhibit Smo by binding to its heptahelical bundle. Currently it is in preclinical and clinical studies as an anticancer agent (Kolterud, Å.; Toftga°rd, R. Drug DiscoVery Today: Ther. Strategies 2007, 4, 229-235). A number of Smo inhibitors have now been reported and can be classified as cyclopamine analogues or synthetic Smo antagonists. Several pharmaceutical companies have identified new Smo inhibitors with druglike properties by optimization of highthroughput screen hits. One such small molecule, GDC-0449, was developed by Curis and Genentech, is currently in phase I/II clinical trials for advanced BCC and solid epithelial tumor (Gunzner, J.; Sutherlin, D.; et al., WO2006028958, Mar. 16, 2006). Despite with these compounds, there still remains a need for potent inhibitors of the hedgehog signaling pathway.

DETAILED DESCRIPTION

OF THE INVENTION

The present invention is related to compounds showed as in Formula (I)

In a particular embodiment, compounds of the invention have the general formular Ia.

Wherein A, R1, R2, R3, R4 and m are as defined herein and

X is absent, O, CR4R7 or NR3
R7 is hydrogen or an optionally substituted C1-4 alkyl group;
In another particular embodiment, compounds of the invention have the general formular Ib.

Wherein A, R1, R2, R3, m are as defined herein and

Y is absent or CR4R7
R4, R7 are as defined herein.

The present invention also relates to compounds as shown in Formula (A):

or a pharmaceutically acceptable salt thereof, wherein:
Y is selected from -K-A1-R1;
K is selected from NR3C(O) and NR4C(O)NR5;
A1 is selected from aryl, heteroaryl, and heterocyclyl;
R1 is one or more substituents independently selected from H, halo, nitro, C1-C6 alkylsulfonyl, —OR4, C1-C6 alkyl, and C1-C6 haloalkyl;

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